Thin tissue layer (8)
I believe the answer is:
membrane
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thin tissue layer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for membrane that I've seen before include "Thin sheet covering organs" , "Thin pliable sheet of material" , "Layer surrounding cells" , "Thin sheet as a barrier" , "Thin pliable sheet of body tissue" .)